Indian officials say at least 26 people have drowned in flooding in the northeastern state of Assam.

The officials say the deaths occurred in the state's western Goalpara district near the border with Bangladesh.

Army helicopters airlifted 20 people, many of whom were clinging to treetops to escape the flash floods. Thousands have moved to relief camps in Assam's main city of Guwahati, after their homes were inundated with rain water.

More than 2,000 people have been killed by flooding and waterborne diseases in South Asia since monsoon rains began in June. Death tolls have been highest in India and Bangladesh.